Cloning of genes which regulate mortality

人正常成纤维细胞具有有限的增殖性LISPAN（正常）。癌细胞通常是无限的寿命（不朽的）。本项目的目的是寻找在正常细胞增殖寿命结束时参与生长抑制的基因。制备了消减cDNA文库，期望富集在衰老细胞中高表达的cDNA。通过系列差异噬斑杂交筛选从文库中选择克隆。通过北方印迹证实这些基因的表达。最终，九个克隆人被选中。经测序和同源性检索，发现4个克隆为未报道序列，4个克隆与已知基因高度同源，其中1个为干扰素诱导基因，1个克隆为已知基因的部分序列，即干扰素诱导基因6-16。考虑到IFN诱导基因或其同源基因的高表达率以及IFN具有生长抑制作用，IFN可能是参与衰老细胞生长抑制的候选基因。IFN-β，而不是IFN-α和IFN-γ，在寿命结束时产生，其中在三个其他IFN-诱导基因中发生高水平诱导，其通过抗IFN-β抗体处理降低。

human normal fibroblasts have a finit proliferative lispan (normal). Cancer cells are generally infinit lifespan (immortal). The purpose of the present project is to search for genes which participate in growth repression at the end of the proliferative lifespan of normal cells. Subtraction cDNA libraies were prepared which is expected to enrich cDNAs that highly expressed in senescent cells. Clones were selected by serial differential plaque hybridization screening from the library. Expression of these genes was confirmed by northern blot. Nine clones were finally selected. By sequencing and homology search of these clones, 4 clones were found to be unreported sequences, 4 clones to be highly homologous to known genes, one of which was interferon (IFN)-inducible gene, and 1 clone to be a partial sequence of known gene, IFN-inducible gene 6-16. Considering that it was unexpectedly high incidence of IFN-inducible gene or its homologue and that IFN has growth repressive effect, IFN can be a candidate of genes which participate on growth supression of senescent cells. IFN-beta, not IFN-alpha and IFN-gamma, was produced at the end of the lifespan where high level induction occurred in three other IFN-inducible genes which was reduced by anti-IFN-beta antibody treatment.